Failed Mandarin duck hatching

[DuckDuckandmoreDucks]

I had bought a few mandarin duck eggs to hatch and all seemed to be going well but all of the eggs hadn’t hatched by their due date. I candled them and found that they seemed to have died. One was still alive and moving though. Over the weekend I was gone and came back to find the last one died. The humidity dropped a little but for the rest of them conditions stayed stable. I would just like anyone’s ideas on what could have happened.

 

[ChickenCanoe]

Probably about a hundred or so different things. Embryonic death early or midway through incubation is likely unrelated to humidity. Weight loss by the end is the most important point regarding humidity.

That leaves us with temperature and turning if incubation was an issue. Also possibly a less than sterile incubator.
The huge unknowns are the eggs themselves. Their age before incubation, handling during storage, age, health and nutrition of the breeders.